1.5 diesel dpf regen.

[Matt92]

Can anyone give me some pointers on how I should drive to regen my car successfully? I know it’s supposed to do it automatically when on a long journey, but it doesn’t appear to. Technically I wouldn’t know when I’m driving if it was doing it or not I guess. 

The reason I ask though, I drove down south at the weekend, hour and a half each way, not all motorway, but a fair bit of 70 in 6th which puts the revs at around 2000. But when I drove to work this morning, about 10 miles when I switched off the engine the fan was running. Temp was fine so I assume it was attempting a regen. Any tips please? 🤞

[TomsFocus]

Simple answer is you can't...  Just let it get on with it and only worry about it if you end several trips in a row with the fans running.  There is an old myth about motorway journeys and 2000rpm+ triggering a 'passive' regen, it's not true at all, the exhaust simply doesn't get hot enough while cruising if you watch live data on the DPF temp sensors.  So it will have to trigger an active regen every few hundred miles.  Trouble is, the PCM isn't psychic, it doesn't know whether you're going to be driving for 10 minutes or 50 minutes and seems to start regens at the worst possible times, usually on a short run the day after a long run, exactly as you've just had lol.

There are some noticeable effects of a regen other than the fan running, the engine note gets a bit deeper and rougher (similar to cold start sound), you get a bit more poke if you accelerate during regen, it can be a bit jerky on light throttle, sometimes you can see smoke of smell the hot cat especially if you stop at lights.  If you're as anal about MPG as I am you can also see it's not doing as many mpg as you'd expect for the road/conditions.  I don't know if the facelift Focus got a 'change down' arrow as well as a change up for gears (preface didn't), but on the Golf it only ever tells me to change down during a regen so that's a sure fire way to tell it's doing one.  It'll regen around town at 30 or less in 2nd, doesn't need speed. 

[isetta]

whilst I have never done a forced regen, if you have a good OBD port device (like the ones from Tunnelrat electronics) and Forscan software you can force it to regen and it also shows the mileage since the last regen.

Some people say that if you are parking as it is doing a regen the best thing to do is to give it a thrash round the block.

I believe if you turn off mid regen you can end up with oil level in the sump getting higher as it is diluted with extra diesel that's been shoved in the engine and not burnt and I assume that reduces the oil quality.

[Matt92]

Thank you for that detailed response Tom. 👍

Being new to diesels, one of the man things I’m worried about is having that little light come on because the dpf is blocked/blocking. I know my use probably isn’t the most suitable for this car, about 10 miles each way to work everyday, but I generally try and do any long runs at the weekend so the car has a chance to regenerate. As you say though it always seems to do it Monday morning when I get to work though but it doesn’t usually happen again for some time.

@isetta I’ve got both FORScan on windows and also on my iPad, so it would be handy if I could use the iPad version to see when it last tried. I’ll have a look sometime. I have in the past left the engine running when I hear the fans running, but normally I park the car and switch off before realising the fans running.

[DaveT70]

You can tell when it goes into "regen" mode as the engine gets noisier, a little bit more responsive because its pushing more fuel through to heat up the DPF, the fans kick in on full power and (if you come to a stop) stop/start will deactivate and the engine idle will raise to about 950RPM.

Plus the temperature guage goes up, slightly.

My MK3.5 used to regen every 1000-1250 miles

The MK4 regens every 400 or so.

If you get into the habit of running on good quality diesel (BP) and giving it a bit of a blow out now and again it negates the need to regen so often.

The PCM has to show full operating temperature (normally 20 minutes into a journey) to go into regen mode.

Try and get into the habit of letting 2nd and 3rd gear rev to about 4,000 RPM if you're attempting to get to motorway speeds instead of changing up early, that blows all the muck out for you. 

And if you do sense that it has gone into regen mode, try to hold a lower gear than normal for about 5 minutes so as the revs stay at about 2,500-3,500 rpm 

[isetta]

when I got my 1.5tdci fiesta I was worried about the regen 'problems'. My previous car was 2007 fiesta 1.6tdci with no dpf. But I do about 35 miles each way to and from work so I reckoned it would be OK. I have done about 45,000 miles now and have never noticed it is doing a regen other than when I park and on turning the engine off and hearing the radiator fans going mental. Everyone says I should be able to feel it when driving but I can't. 

[TomsFocus]

7 hours ago, Matt92 said:

Thank you for that detailed response Tom. 👍

Being new to diesels, one of the man things I’m worried about is having that little light come on because the dpf is blocked/blocking.

@isetta

Is there a DPF light on the facelift?  There wasn't on the MK3 or MK2.5... 😮

My journeys definitely aren't suited to a DPF, I can't travel far due to health conditions but can't afford to fuel a petrol either.  Most of my journeys are short and cold, with just one 'long' journey a week, but even that's only 16 miles each way.

On the MK2.5 I was doing 12k a year and had to replace the blocked DPF soon after buying it (46k miles!) but eventually had to remove it altogether after it blocked again...that was the eolys additive type though, they never were up to the job!

Both the MK3 Focus and my current Mk6 Golf have coated DPFs and I only do about 6k a year now.  And while I get a lot more regens than most people, I've still never seen the light come on yet.  The Golf has done over 100k now and the worst I've had was 5 short, cold trips in a row with the fans running after each one but the light still didn't come on, tbh I was more worried about the fans killing the battery lol!  The 6th trip was a longer one where it was able to regen...

I'd say it really isn't worth worrying about now we've got coated DPFs.  They seem to be fine unless you literally only do a mile or two per day.

 

[Matt92]

Ok, thanks again to all for those replies. 

Well it seems like the dpf perhaps isn’t as bad as my mind keeps telling me. I think working as a mechanic and seeing broken cars all day everyday, it sort of makes me nervous of my own car. Never thought about my old focus letting me down, I’d go anywhere in that, but I know with all the sensors on the newer cars that one can die at anytime and that’s your engine in limp mode. 🤢

I’ll carry on as I am, do as many long journeys as I can at the weekends.

Oh yeah, and @TomsFocus I am pretty anal about MPG, I’ve got a spreadsheet on my computer to calculate it and have to log it every time I fill up.🤣 The average in the car always seems pretty good though, usually about 1 mpg higher than what I work out with my spreadsheet, but then there’s going to be human error in my filling technique.

[TomsFocus]

10 hours ago, Matt92 said:

Oh yeah, and @TomsFocus I am pretty anal about MPG, I’ve got a spreadsheet on my computer to calculate it and have to log it every time I fill up.🤣 The average in the car always seems pretty good though, usually about 1 mpg higher than what I work out with my spreadsheet, but then there’s going to be human error in my filling technique.

I was even sad enough to graph it recently...    The Mk3 preface trip computer was horrendously bad, 5mpg out half the time and always over read!   It only lasted 4 tanks/2400 miles though lol.  Yet another area in which the Mk2.5 was better!